Marion did not get along very well with Sumter or Moultrie but he got along very well with Lighthorse Harry Lee. Greene ordered Sumter to take on Colonel Coates and the 19th Regiment afoot and put Lighthorse Harry Lee and Francis Marion under Sumter's command. Sumter outranked Marion as a general in the militia, but Marion outranked Sumter in the Continental army. At the Battle of Quinby Bridge, Marion took 58 casualties and Lee took a lot, and they swore that they would never allow their men to be commanded by Thomas Sumter. Greene cut Sumter loose and he went to North Carolina to recruit because he was a loose cannon. Marion would not have anything to do with Sumter's Law, a policy that Sumter wanted to instigate that if people joined the American cause, they would receive a slave after the war. The slaves would be robbed from Tory plantations, and officers of a higher rank would receive more than one. Marion would have nothing to do with it. He was concerned about reconciliation and wanted people to be able to live together after the conflict ceased.
Fort Motte was a very well-fortified plantation house, and Mrs. Motte had been moved out of it. Once the fires could be seen at the High Hills of the Santee, which meant that Rawdon was moving down from Camden, they realized that they had to take Fort Motte or or Rawdon would relieve it. They decided the only way to do it was to set it on fire. Marion was a successful planter but not considered aristocracy, as Lee was. Lee was practically considered royalty from Virginia, so Marion asked Lee to approach Mrs. Motte and she said yes. The house was burned slightly, and the British surrendered, and then Marion had the fire put out.
Next came the Battle of Eutaw Springs, which followed Parker's Ferry, which had cost the British 125 men. At Eutaw Springs, there were three units of militia in the front line. Greene had tried that at Guilford Courthouse and it hadn't worked. It had worked at Cowpens. So, at Eutaw Springs, on the left, you had Andrew Pickens, in the middle the North Carolina militia, and on the right, you had Francis Marion in command of all three units. On his right was Lighthorse Harry Lee. The battle was extremely bloody and brutal. Both sides claimed victory, but 53 British were left seriously wounded on the field and they didn't bury their dead. After the Battle of Eutaw Springs, Lee reported that most of the army was seriously ill. It is thought that Marion's men stayed healthy because they stayed at Cantey's plantation, separated from the big encampments.
It is apparent from reading the correspondence from Greene to Marion, and writings of Lee and Governor Rutledge, they all consider Marion to have been a major player and part of the overall strategy that brought defeat to the British.